#include <stdio.h>
int main()
{
	double sum = 0, num = 1,mu = 1,i,  flag = 1;
	for (i = 1; i <= 100; i++)
	{
		sum = sum + num;
		mu += 1;
		flag = -flag;
			num = 1.0 / mu * flag;
	}
	printf("sum =%.2f", sum);
	return 0;
}